The present invention concerns an electronic watch comprising an oscillator delivering pulses to the input of a frequency division chain composed of two parts, and decoding circuits and display circuits and a source of electrical energy. One of the poles of the source is connected to the ground of the watch and furnishes and initial continuous voltage intended to feed at least the oscillator and the first part of the division chain.
In electronic watch circuits of the C-MOS type ("complementary MOSFET"), it is preferable to operate the oscillator and the first division stages at a low logic level which corresponds to the battery voltage. Weak excitation of the quartz is obtained in this manner, thus ensuring good frequency stability, on the other hand, the losses in the divider, which are proportional to the frequency and to the square of the voltage, remain minimum.
However, the output stages should, in many cases, operate at higher voltages, the value of which depends on the display device. In those cases, an interface is necessary which must be able to be controlled by the low amplitude signals delivered by the first part of the divider chain and furnish signals of greater amplitude capable of controlling the rest of the circuit working at a higher voltage. The chief problems raised by these interface circuits are the cost and the reliability. In fact, some parameters of the transistors composing them should be closely monitored, in the absence of which current consumption becomes excessive.
The object of the present invention therefore is a watch of the above-mentioned type in which the interface stage is particularly sure and reliable. The parameters of the transistors of which it is composed are not subjected to any special constraints, whilst they ensure a reduced current consumption.